1. Field of the Invention
The present invention relates to hand trucks, and more particularly to single axle hand trucks having load shifting apparatus. The load shifting apparatus is employed to assist in inclining the hand truck from a vertical stance in preparation for wheeling the hand truck and its load to a new location.
2. Description of the Prior Art
In operation, hand trucks are usually loaded with bulky and heavy objects when the load bearing frame of the hand truck is substantially vertical. The load is placed on a supporting plate, or load plate. To roll the loaded hand truck to a new location, the hand truck is tilted from its initial vertical stance and drawn or pushed by hand. When the hand truck arrives at its destination, where it is unloaded, it is again placed in the vertical stance. It is often very difficult for a single person to tilt and upright the hand truck if the load is heavy or particularly bulky.
Modifications to hand trucks for shifting loads and the center of gravity have been proposed in the prior art. U.S. Pat. No. 3,746,360, issued to Burdette B. Crawford on Jul. 17, 1973, sets forth an arrangement enabling a load bearing frame of a hand truck to be tilted and supported on a member engaging the ground. However, in the hand truck of Crawford, the main load bearing wheels are mounted on side frames which are vertically slidably connected to the load bearing frame and load plate. By contrast, the load bearing frame of the present invention is monolithic in that there are no relatively moving parts corresponding to the side frames of Crawford. The device of Crawford includes a hand operated linkage absent in the present invention. The present invention utilizes a hand operated lever pivotally fixed to the axle to accomplish load shifting, whereas the device of Crawford causes the main wheels to be retracted relative to the load bearing frame and load plate.
A hand truck seen in U.S. Pat. No. 2,607,606, issued to Stanley S. Millen on Aug. 19, 1952, has an auxiliary axle disposed below the principal axle and located near the load plate, in the manner of the present invention. The auxiliary axle supports rollers which supplement the principal wheels. Unlike the device of Millen, the present invention has only a single axle and a lever which selectively engages the frame of the novel hand truck, thereby shifting the load of the hand truck from the vertical to a tilted position.
U.S. Pat. No. 2,653,033, issued to Joseph C. Chinette, et al., on Sep. 22, 1953, describes a hand truck which is adjustable to vary position of the load plate relative to the principal wheels. However, there is no lever which selectively engages the frame when shifting the load as the hand truck is inclined from the vertical, as seen in the present invention.
A hand truck seen in U.S. Pat. No. 2,710,106, issued to Alfred H. Hanson on Jun. 7, 1955, includes spurs fixed solidly to the frame which engage the ground when a load is being shifted. However, the hand truck of Hanson does not utilize a lever to shift the load from the vertical stance to a tilted position, as in the present invention.
In U.S. Pat. No. 4,762,333, issued to Carl N. Mortenson on Aug. 9, 1988, the wheels are movable relative to the load bearing frame, whereas the wheels are rotatably mounted in fixed location on the load bearing frame in the present invention. Load shifting is accomplished by Mortenson with the weight of the load and hand truck imposed on the wheels. In the present invention, a frame engaging lever pivotally mounted to the axle assists in shifting the load from the vertical stance to a tilted position.
U.S. Pat. No. 5,118,124, issued to Craig F. Storay, et al., on Jun. 2, 1992, illustrates another hand truck wherein the main wheels are adjustably positioned relative to the load bearing frame. In the device of Storay, et al., rockers come to contact the ground and temporarily support the load bearing frame. By contrast, the present invention utilizes only a single axle and pair of wheels, and an axle mounted lever for assisting in shifting the load from the vertical stance to a tilted position.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.